Eukaryotic Cell Division

PurposeIncrease cell number for growth, maintenance, repair, or reproduction

Cell TypesSomatic Germ

Cell Division CycleInterphase Nuclear Division (Mitosis or Meiosis)Cytokinesis

Fig. 5.1a

TERMINOLOGY

Genetic MaterialStructural Types

Chromatin Uncoiled genetic material not visible

with a light microscope.Chromosome Coiled genetic material visible with

a light microscope.

Fig. 5A

TERMINOLOGYGenetic Material

Structural Apparatus Sister Chromatids

One of two identical copies of genetic material attached at the centromere.Centromere Constricted portion of a chromosome that holds sister chromatids together.Kinetochore Protein structure at the centromere to

which spindle fibers attach.

TERMINOLOGYCentrioles

Cylindrical structure within a centrosome producing spindle fibers.

TERMINOLOGYMitotic Spindles (Spindle Fibers)

Microtubules that bring about chromosomal movement.

SOMATIC CELL DIVISIONSomatic Cells

DefinitionAll diploid cells that are not involved in

gamete formation.Examples

Skin, Heart, Liver, Intestinal, Bone, MuscleType of Cell Division

Mitotic (Mitosis) Steps

InterphaseMitosisCytokinesis

SOMATIC CELL DIVISIONMitotic Cell Division

OutcomeEach daughter cell is a clone of the

parent. Each cell has homologous pairs (diploid, 2N) of chromosomes.

Human Karyotype46 chromosomes

. 22 paired autosomes . 2 sex chromosomes ( XX or XY)

KARYOTYPE

Sex Chromosomes

Autosomes#1-22

Homologous Pairs, Diploid, 2N

Humanoid Daughter’s Old Boyfriend 22.9

MITOTIC CELL DIVISIONInterphase

Purpose Preparation for cell division.

Steps G1 (Gap 1) Phase

S Phase (Synthesis)G2 (Gap 2) Phase

Genetic MaterialChromatin

INTERPHASEG1 (Gap 1) Phase

Undividing Cell1) Cell growth2) Cell metabolism

Dividing Cell 1) Organelles begin to replicate

2) Preparation for S phase a) DNA is checked for damage b) Environment is checked for adequacy

c) Cell size is checked

Fig. 5.1b

G1 PHASE

INTERPHASES (Synthesis) Phase DNA replication

Formation of Sister Chromatids

DNA REPLICATION

Sister Chromatids

INTERPHASEG2 (Gap 2) Phase

Final preparation for mitosis.Check for DNA damageCheck to see that S phase is completeCheck the environment for adequacyFinish Organelle Replication

Fig. 5.1b

MITOTIC CELL DIVISION

MitosisPurpose

Nuclear division Separation of sister chromatids

StepsProphaseMetaphaseAnaphaseTelophase

MITOSISProphase

1) Chromatin coils becoming chromosome.2) Nuclear envelope disintegrates.3) Centrioles produce mitotic spindles and move toward the spindle poles4) Kinetochore fibers attach to kinetochores5) Polar fibers run from pole to pole6) Asters attach centrioles to plasma

membrane

MITOSIS

MetaphaseCentriole movement aligns chromosomes at

the spindle equator. M Checkpoint for spindle fiber attachment.

MITOSIS

Anaphase1) Kinetochores pull on Kinetochore fibers2) Sister chromatids separate.

a) Chromatids are now referred to as “Daughter Chromosomes”.

3) Daughter chromosomes move toward opposite spindle poles.

Daughter Chromosome

MITOSIS

Telophase1) Chromosomes arrive at spindle poles.2) Nuclear membrane regenerates.3) Spindle fibers disintegrate.4) Chromosomes become chromatin.

CYTOKINESISPurpose

Formation of two daughter cells. Types

Animal Cell Cleavage Furrow

Formation of a contractile ring at the cell equator which will "pinch“ the cell in two.

Plant Cell Cell Plate

Construction of a new cell wall inside of the cell creating two cells.

ANIMAL CYTOKINESIS

ANIMAL CYTOKINESIS

DAUGHTER CELLS

PLANT CYTOKINESIS

PLANT CYTOKINESIS